Propagation Properties Of Surface Plasmonic Waveguides And Anomalous Transmission Characteristics Of Micro - Nanostructured Light

Surface plasmon polaritons(surface plasmon polaritons,SPPs) are electromagnetic waves that propagate along metal-insulator interface and formed by the interference between the electron at the surface of a metal film and the photon. Since the electromagnetic field of SPPs are tightly bound to the vicinity of the surface beyond the conventional diffraction limit, and thus may provide a promising way to realize ultra-compact photonic integrated circuits. In addition, the design and application of photonic devices about SPPs is currently the international frontier research direction. The thesis mainly uses the finite element method (FEM) and the finite difference time domain (FDTD) method, to study the optical transmission characteristic of the surface plasmon waveguide and the extraordinary optical transmission of the subwavelength circular nanohole. In addition, the impact of the structure parameters on the propagation characterstics of the surface plasmon waveguide and subwavelength circular nanohole is studied. The main research works of this thesis are listed as follows:1. Since the MIM waveguide has the advantages of the better mode restriction, less energy loss, longer transmission distance. A metal-insulator-metal (MIM) waveguide with L shaped resonator based on SPPs is designed. The results show that several stopbands appear in the transmission spectra, the filtering properties of this resonator rely on the size of the L shaped cavity. In addition, the MIM waveguide with L shaped cavity allows for a much more sensitive detection of small refractive index changes of the filled media inside the nanocavity, which reveals a potential sensors application of the MIM waveguide with L shaped cavity. Furthermore, we presented the structure that the different size L cavities are placed on both sides of the waveguide. Compared with a single L shaped resonator, the two L resonator can improve the filter of the long stopband wavelength and can also improve the bandpass characteristics of short wavelength.2. We designed a circular resonator embedded with the cross structure based on the metal-insulator-metal waveguide. The transmission properties of this composite resonator were numerically investigated by the finite-difference time-domain method. The results show that the rotated cross structure destroys the symmetry of the resonant mode of SPPs in the empty circular cavity, which results in novel filter function of the complex resonator. The filter function of a circular resonator embedded with the cross structure depends on the rotating angle of the cross structure. Compared to θ=0°case, when the cross structure rotate to a certain angle, there is only one transmission peak in the transmission spectra. In addition, the transmission properties of the composite resonator are strongly dependent on the cross structure size. These results would be helpful for designing composite filters with specific usage。3. Since hybrid waveguide has the advantages of the strong confinement and the long propagation length, it was paid widely attention. In this paper, the impact of the metal nanowire on the propagation characteristics of the hybrid waveguide used the finite element method is studied. The nanowire is paralleled placed on the near the hybrid waveguide. The results show that the propagation characteristics strongly rely on the length of the metal nanowire contributed by the formed surface plasmon polaritons resonance in the coupling area. In addition, the effects of the radius of the metal nanowires, the refractive index of dielectric substrate, and the distance between the two nanowires on the propagation characteristics are also studied. These results here provide a theoretical foundation for the applications of the hybrid nanowire waveguide.4. The nonresonant extraordinary optical transmission (EOT) can achieve broadband transmission, which is significant for the collection and excitation of the broadband light. To obtain broadband transmission, in this paper, we proposed a subwavelength metallic circular nanohole arrays. The structure is composed of metal film on a quartz substrate, the circular nanohole in the metal film. The transmsission properties of the metallic circular nanohole arrays were investigated using the finite element method. Results show that this paradigm structure can achieve broadband transmission. In addition, the effects of the polarization direction, the radius of the holes and the period of the arrays on the transmission property were also studied.